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From: gilmore@macc.wisc.edu
Newsgroups: comp.sys.amiga.tech
Subject: Re: Integer sine calculations?
Message-ID: <4798@dogie.macc.wisc.edu>
Date: 23 Nov 90 12:47:20 GMT
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Distribution: comp
Organization: University of Wisconsin Academic Computing Center
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In article <HEBRAIS.90Nov23024202@olivier.IRO.UMontreal.CA>, hebrais@olivier.IRO.UMontreal.CA (Philippe Hebrais) writes...

>   In article <7336@hub.ucsb.edu> 6600mage@ucsbuxa.ucsb.edu (Orion Wilson the Passable) writes:
>   >My question is how these paths are computed. The
>   >number of objects and their speed incidates that
>   >they aren't being done by floating-point techniques,
>   >and i'm pretty sure the numbers are not
>   >pre-calculated, so it seems that smooth curves like
>   >the sin and cos can be done using integer (native
>   >MC68000) arithmatic.

If you use pre-calculated values for sine and cosine, it doesn't take up 
much space, and speeds things up considerably. As well, if the number of 
possible positions is 200, it only takes 200 * 2 (x and y) * 2 (bytes 
per word) 800 bytes, which isn't all that much, and speeds up even more. 
I know guys who never use the sin and cos, they just use a .1 degree 
table for the functions, as even in floating-point, the size of the 
table is dwarfed by the extra junk that X adds on....